Sloped, Flat, or Both?

VietGnome · Monday at 1:58 PM

I'm undecided and torn about which way to go for my 30x40 build.

Floors will not have drains. That would be preferred but it's just not an option with codes and the like.

I'm on East Coast Canada so winters are very much a thing, and will absolutely see vehicles, small tractor with blower, and 4 wheeler with plow parked in there. Big duck hunter so the boat will often get parked in there in the fall to dry out between hunts.

I've always assumed it would have a light grade, but reading old posts here it seems quite divided. I also will have a side 8x8 door, and can see the 1-2" drop from the grade over than span causing sealing issues (I haven't discussed options regarding this with the concrete guy yet, but I'm sure there's a solution.)

The other option would be to have the back 15-20ft of the "shop area" poured flat, and have it transition to a slight grade for the front half(ish) of the shop where vehicles will be parked.

What's everyone's thoughts with similar climate/use case?

Carchie · Tuesday at 12:02 AM

Go with the split design. Keeping the back 20ft flat gives you a solid, stable area for toolboxes and shop equipment, while the slight grade up front handles the winter melt from your vehicles and tractor perfectly.

TurnipTruck · Tuesday at 9:57 AM

I had the front third sloped to a drain trench and the back 2/3rds flat.
During heavy snow years I have to pump out the trench maybe twice a winter.

VietGnome · Tuesday at 9:59 AM

Carchie said:
Go with the split design. Keeping the back 20ft flat gives you a solid, stable area for toolboxes and shop equipment, while the slight grade up front handles the winter melt from your vehicles and tractor perfectly.

I wish I could have a drain but it would be such a shitshow.

I haven't decided on what portion I want sloped at the front, but I'm leaning towards that.

Doing the first 15-20ft sloped seems like the best of both worlds.

How big is your shop?

Dig Doug · Tuesday at 10:23 AM

We set this drain up just outside the garage it’s in the Az. desert

Each section of track drain has slope ( fall ) built into it so any water will naturally drain out, the top ( drain grate ) is set level and then you slope the concrete 1/8- 1/4inch foot slope towards the drain

the drain materials were about $2,000 for this set up back in 2024/25 its about 30ft +/- long

this is a BIG issue / decision for you as you only do it once and then it’s DONE for ever !
I don’t think I would like it sloped out and having to deal with water seeping out from under the garage doors and then potentially Icing over right at the door & driveway

I like the way @TurnipTruck set his up, Really Clean look

VietGnome · Tuesday at 10:55 AM

Dig Doug said:
We set this drain up just outside the garage it’s in the Az. desert

Each section of track drain has slope ( fall ) built into it so any water will naturally drain out, the top ( drain grate ) is set level and then you slope the concrete 1/8- 1/4inch foot slope towards the drain

the drain materials were about $2,000 for this set up back in 2024/25 its about 30ft +/- long

this is a BIG issue / decision for you as you only do it once and then it’s DONE for ever !
I don’t think I would like it sloped out and having to deal with water seeping out from under the garage doors and then potentially Icing over right at the door & driveway

I like the way @TurnipTruck set his up, Really Clean look

The problem with drains here, is they're required to be tied into my septic, require more approvals, inpections, oil separators, and in my situation possibly a pump, etc.

larry_g · Tuesday at 11:53 AM

VietGnome said:
I'm undecided and torn about which way to go for my 30x40 build.

Floors will not have drains. That would be preferred but it's just not an option with codes and the like.

I'm on East Coast Canada so winters are very much a thing, and will absolutely see vehicles, small tractor with blower, and 4 wheeler with plow parked in there. Big duck hunter so the boat will often get parked in there in the fall to dry out between hunts.

I've always assumed it would have a light grade, but reading old posts here it seems quite divided. I also will have a side 8x8 door, and can see the 1-2" drop from the grade over than span causing sealing issues (I haven't discussed options regarding this with the concrete guy yet, but I'm sure there's a solution.)

The other option would be to have the back 15-20ft of the "shop area" poured flat, and have it transition to a slight grade for the front half(ish) of the shop where vehicles will be parked.

What's everyone's thoughts with similar climate/use case?

You are confusing flat and level. You want your floor level or sloped. Either surface can be flat or textured. When talking to a concrete guy level is just that, or sloped specified is height change per foot. Flat is a measured high to low over some distance like no more than +/- .10" over 10'. You can have flat walls that are plumb but that is a different discussion. That said when I built my building it was to be a fabrication shop and that got me around having to slop the floor. If I understand correctly you want to park vehicles in the building that are dripping so a slope is desired. It sounds to me like 1/2 level and 1/2 sloped is what will work the best for you.

lg
no neat sig line

VietGnome · Tuesday at 12:10 PM

larry_g said:
You are confusing flat and level. You want your floor level or sloped. Either surface can be flat or textured. When talking to a concrete guy level is just that, or sloped specified is height change per foot. Flat is a measured high to low over some distance like no more than +/- .10" over 10'. You can have flat walls that are plumb but that is a different discussion. That said when I built my building it was to be a fabrication shop and that got me around having to slop the floor. If I understand correctly you want to park vehicles in the building that are dripping so a slope is desired. It sounds to me like 1/2 level and 1/2 sloped is what will work the best for you.

lg
no neat sig line

Im aware of the difference between flat and level, i just mistyped. The context is talking about level.

Sounds like 1/2 and 1/2 is the way!

CoogarXR · Tuesday at 1:43 PM

I did half and half on my 30x50. I did a center drain on the "car" side, and level on the office/bathroom side.

I live in the boonies, no codes, laws, etc, so I just had my floor drain empty down the hill behind my shop. All it will ever see is melted snow anyway.

VietGnome · Tuesday at 1:46 PM

CoogarXR said:
I did half and half on my 30x50. I did a center drain on the "car" side, and level on the office/bathroom side.

I live in the boonies, no codes, laws, etc, so I just had my floor drain empty down the hill behind my shop. All it will ever see is melted snow anyway.

Just what I needed to hear.

Lots of people to unpermitted in my neck of the woods, but it's not a risk I wanted to take. Permit is only $300.

Had some locals recommend i do a drain the way I want and just throw a sheet of plywood on it for the inspection, but that's really a headache I don't need.

ConCretin · Tuesday at 3:14 PM

If you don't want to mess with floor drains, how about a simple sump with a grate under each of the vehicle parking areas. You could just hang a form and place them integrally with the slab. Is it preferable to pump or vacuum out a sump rather than. deal with water pooling in the corners and running under your overhead doors and freezing? Idk.

I have floor drains under each vehicle that drain a 10x 20 area that pitches 1/4" per foot across and 1/8" per foot the long way. All the water just disappears under the vehicle. You could so the same with sumps. Just a thought.

VietGnome · Tuesday at 3:33 PM

ConCretin said:
If you don't want to mess with floor drains, how about a simple sump with a grate under each of the vehicle parking areas. You could just hang a form and place them integrally with the slab. Is it preferable to pump or vacuum out a sump rather than. deal with water pooling in the corners and running under your overhead doors and freezing? Idk.

I have floor drains under each vehicle that drain a 10x 20 area that pitches 1/4" per foot across and 1/8" per foot the long way. All the water just disappears under the vehicle. You could so the same with sumps. Just a thought.

Hmm I've never actually thought of that being a possibility. I'll have to look into this and see how it works with regards to codes and the like.

Have you ever seen these before? How deep would they usually go? Might be a great alternative

Edit: as well as any freezing risks with it sitting below grade?

TurnipTruck · Tuesday at 4:10 PM

My trench drain (referenced above) is just a 30’ wide sump parallel to the overhead doors that catches all the snowmelt until it needs pumping out with an electric sump pump. No drain, but I could just drill holes if I thought it needed to self drain.
I asked the mason for a “shovel-wide and shallow enough to set grating on”, but I’m glad he decided to make it 12” deep.

Here I am shoveling the muck out for the first time after eight years accumulation of dirt/leaves/snowmelt/salt/moose blood.

There is no danger of freezing as long as your building is heated and the doors aren’t left open.

VietGnome · Tuesday at 4:15 PM

TurnipTruck said:
My trench drain (referenced above) is just a 30’ wide sump parallel to the overhead doors that catches all the snowmelt until it needs pumping out with an electric sump pump. No drain, but I could just drill holes if I thought it needed to self drain.
I asked the mason for a “shovel-wide and shallow enough to set grating on”, but I’m glad he decided to make it 12” deep.

Here I am shoveling the muck out for the first time after eight years accumulation of dirt/leaves/snowmelt/salt/moose blood.

There is no danger of freezing as long as your building is heated and the doors aren’t left open.

Fantastic! Very intriguing!

Its just a concrete pit with the lip to set the grate in? Nothing else?

Seems like the best alternative, minus the price of steel grates.

TurnipTruck · Tuesday at 4:24 PM

It’s just a hole. I used scraps of 2x6 for several years until I salvaged enough grating.

maybe check out my build linked below, since our buildings are similar.

ConCretin · Tuesday at 5:01 PM

VietGnome said:
Hmm I've never actually thought of that being a possibility. I'll have to look into this and see how it works with regards to codes and the like.

Have you ever seen these before? How deep would they usually go? Might be a great alternative

Edit: as well as any freezing risks with it sitting below grade?

Sumps are a common element in commercial construction and we've installed hundreds. I would think a 12" deep sump by whatever size grate you can find would be adequate. Btw, when you form them up, add a form to create a lip support the grate for a clean install.

I don't think freezing would be a structural concern although frozen water could build up and make the sump ineffective. You might be surprised how resistant to freezing an in-slab sump might be given the natural heat from below.

Dig Doug · Wednesday at 12:49 AM

We’ve done a lot of catch basins for sump pumps

if you can bootleg in a electric conduit & a PVC drain line ( maybe set back in one wall of the pit you can drop in a float sump pumps
Float works like a toilet float float raises turns on pumps out float lowers turns off ) the pumps have a long cord and are designed to for this application

It is best to keep the pump raised off the bottom of the pit so it doesn’t **** up a lot of dirt /grit
pits can be 18x18x18 or larger to small and it’s awkward to clean out and have access

example of a pump

VietGnome · Wednesday at 12:57 AM

Dig Doug said:
We’ve done a lot of catch basins for sump pumps

if you can bootleg in a electric conduit & a PVC drain line ( maybe set back in one wall of the pit you can drop in a float sump pumps
Float works like a toilet float float raises turns on pumps out float lowers turns off ) the pumps have a long cord and are designed to for this application

It is best to keep the pump raised off the bottom of the pit so it doesn’t **** up a lot of dirt /grit
pits can be 18x18x18 or larger to small and it’s awkward to clean out and have access

example of a pump

Looks like I can either get a 17x17x24 catch basin insert with a galvanized grate that I can drop into each bay, or look for several grates and do a longer 12" deep style trench in each bay. The former seems like it will be cheaper. Only around $300 in materials.

The issue with a pump is as soon as I add a drain line and pump its an instant code violation. That's why I was now considering just a catch basin and shop vac or pump out as required.

Dig Doug · Wednesday at 1:05 AM

A regular pump w/ garden hose works ! Instead of a shop vac
my shop vacs are always dirty or have bags in em - I hate getting them wet

I have 2 of these
screw a garden hose as A discharge hose and drop in a pump

only issue will be keeping an eye on the water levels in the pit

Dig Doug · Wednesday at 1:11 AM

A floor blower fan might work to evaporate some of the water in the pit

let if blow across the drain grate and it might help the water go away

Paving · Wednesday at 2:44 AM

Go half-an—half with the concrete. You can also use 24” x 24” x 24” catch basin systems

Paving · Wednesday at 2:51 AM

Dig Doug said:
We set this drain up just outside the garage it’s in the Az. desert

Each section of track drain has slope ( fall ) built into it so any water will naturally drain out, the top ( drain grate ) is set level and then you slope the concrete 1/8- 1/4inch foot slope towards the drain

the drain materials were about $2,000 for this set up back in 2024/25 its about 30ft +/- long

this is a BIG issue / decision for you as you only do it once and then it’s DONE for ever !
I don’t think I would like it sloped out and having to deal with water seeping out from under the garage doors and then potentially Icing over right at the door & driveway

I like the way @TurnipTruck set his up, Really Clean look

You prefer to suspend these Swiftdrains with wood and not rebar?

Dig Doug said:
We set this drain up just outside the garage it’s in the Az. desert

Each section of track drain has slope ( fall ) built into it so any water will naturally drain out, the top ( drain grate ) is set level and then you slope the concrete 1/8- 1/4inch foot slope towards the drain

the drain materials were about $2,000 for this set up back in 2024/25 its about 30ft +/- long

this is a BIG issue / decision for you as you only do it once and then it’s DONE for ever !
I don’t think I would like it sloped out and having to deal with water seeping out from under the garage doors and then potentially Icing over right at the door & driveway

I like the way @TurnipTruck set his up, Really Clean look

Thats a clean install. You prefer to suspend these with wood instead of using the rebar supports?

Sloped, Flat, or Both?

Well-known member

Member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Member

Member